Bigger is always better, particularly where the reservoir tank is concerned. Sand/bead blasting takes up a huge volume of air, and sanders use a lot too. Look at the CFM rating at the low end of the pressure scale, like 25 CFM at 75 PSI, for instance. That's the spec that will determine how long you can run a tool before giving the tank a chance to build pressure again. I'd suggest a minimum of a 50-gallon tank, and 100 would be better. Of course, I'm accustomed to supplying a professional shop with several employees working, so a 100 CFM compressor capable of maintaining 100 PSI or more at full flow was what I considered to be minimum capacity. I ran two 20 HP compressorss with 300 gallon reserve tanks in the last body shop I managed. You don't need that much for a hobby operation.
Jerry
